Material test structure

ABSTRACT

Material test structures having cantilever portions and methods of forming the same are described herein. As an example, a method of forming a material test structure includes forming a number of electrode portions in a first dielectric material, forming a second dielectric material on the first dielectric material, wherein the second dielectric material includes a first cantilever portion and a second cantilever portion, and forming a test material on the number of electrode portions, the first dielectric material, and the second dielectric material.

PRIORITY INFORMATION

This application is a Divisional of U.S. application Ser. No. 13/458,048filed Apr. 27, 2012, the specification of which is incorporated hereinby reference.

TECHNICAL FIELD

The present disclosure relates generally to material test structures andmethods, and more particularly to material test structures havingcantilever portions.

BACKGROUND

Memory devices are utilized as non-volatile memory for a wide range ofelectronic applications in need of high memory densities, highreliability, and data retention without power. Memory devices aretypically provided as internal, semiconductor, integrated circuits incomputers or other electronic devices. There are many different types ofmemory, including random-access memory (RAM), read only memory (ROM),dynamic random access memory (DRAM), synchronous dynamic random accessmemory (SDRAM), flash memory, and resistive memory, among others. Typesof resistive memory include phase change random access memory (PCRAM)and resistive random access memory (RRAM), for instance.

Various memory cells, such as resistive memory cells include a resistivestorage element whose resistance can be adjusted to represent a numberof different data states. For instance, voltage and/or current pulsescan be applied to such resistive memory cells to program the resistivestorage element to a particular resistance level corresponding to aparticular data state, and the particular data state of the cell can beread by determining the resistance level of the resistive storageelement, e.g., by sensing a current through the cell responsive to anapplied voltage.

As an example, resistive storage elements can include a resistancevariable material, such as a phase change material or metal oxide,formed between a pair of electrodes. The properties of a resistancevariable material can affect the characteristics of a memory cellcomprising the particular resistance variable material. As such, it canbe useful to test the properties, e.g., physical and/or electricalproperties, of different memory cell materials and/or alloys thereof.However, testing various different memory cell materials withoutcontaminating production tools and/or the memory cell materialsthemselves can be challenging. In addition, fabrication of teststructures used to test different memory cell materials can be timeconsuming and process intensive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1B illustrate cross-sectional views of material test structuresin accordance a number of embodiments of the present disclosure.

FIGS. 2A-2C illustrate various process stages associated with forming amaterial test structure in accordance with a number of embodiments ofthe present disclosure.

FIGS. 3A-3B illustrate cross-sectional views of material test structuresin accordance a number of embodiments of the present disclosure.

FIGS. 4A-4F illustrate various process stages associated with forming amaterial test structure in accordance with a number of embodiments ofthe present disclosure.

DETAILED DESCRIPTION

Material test structures having cantilever portions and methods offorming the same are described herein. As an example, a method offorming a material test structure includes forming a number of electrodeportions in a first dielectric material, forming a second dielectricmaterial on the first dielectric material, wherein the second dielectricmaterial includes a first cantilever portion and a second cantileverportion, and forming a test material on the number of electrodeportions, the first dielectric material, and the second dielectricmaterial.

Embodiments of the present disclosure can provide material teststructures that are isolated, e.g., electrically, from adjacent materialtest structures. Embodiments of the present disclosure can also includeforming the test material on electrodes, which are not affected byfurther processing after the formation and planarization of theelectrodes.

In the following detailed description of the present disclosure,reference is made to the accompanying drawings that form a part hereof,and in which is shown by way of illustration how one or more embodimentsof the disclosure may be practiced. These embodiments are described insufficient detail to enable those of ordinary skill in the art topractice the embodiments of this disclosure, and it is to be understoodthat other embodiments may be utilized and that process, electrical,and/or structural changes may be made without departing from the scopeof the present disclosure.

The figures herein follow a numbering convention in which the firstdigit or digits correspond to the drawing figure number and theremaining digits identify an element or component in the drawing.Similar elements or components between different figures may beidentified by the use of similar digits. For example, 112 may referenceelement “12” in FIG. 1, and a similar element may be referenced as 212in FIG. 2D. Also, as used herein, “a number of” a particular elementand/or feature can refer to one or more of such elements and/orfeatures.

FIGS. 1A-1B illustrate cross-sectional views of material test structuresin accordance a number of embodiments of the present disclosure. FIG. 1Aillustrates a cross-sectional view of a material test structure 150having one level of cantilever portions in accordance with a number ofembodiments of the present disclosure. In one or more embodiments,material test structures can include a number of levels of cantileverportions. The material test structure 150 includes a test material 122whose properties, e.g., physical and/or electrical characteristics, canbe tested and observed using the material test structure of the presentdisclosure. The material test structure 150 can be used to simulateoperation of a memory cell during the testing of different testmaterials. The test material 122 can be, for example, a resistancevariable material, e.g., a phase change material. The test material canbe a chalcogenide, e.g., a Ge-Sb-Te (GST) material such as Ge₂Sb₂Te₅,Ge₁Sb₂Te₄, Ge₁Sb₄Te₇, etc., among other resistance variable materials.The hyphenated chemical composition notation, as used herein, indicatesthe elements included in a particular mixture or compound, and isintended to represent all stoichiometries involving the indicatedelements. Other resistance variable materials can include Ge-Te, In-Se,Sb-Te, Ga-Sb, In-Sb, As-Te, Al-Te, Ge-Sb-Te, Te-Ge-As, In-Sb-Te,Te-Sn-Se, Ge-Se-Ga, Bi-Se-Sb, Ga-Se-Te, Sn-Sb-Te, In-Sb-Ge, Te-Ge-Sb-S,Te-Ge-Sn-O, Te-Ge-Sn-Au, Pd-Te-Ge-Sn, In-Se-Ti-Co, Ge-Sb-Te-Pd,Ge-Sb-Te-Co, Sb-Te-Bi-Se, Ag-In-Sb-Te, Ge-Sb-Se-Te, Ge-Sn-Sb-Te,Ge-Te-Sn-Ni, Ge-Te-Sn-Pd, and Ge-Te-Sn-Pt, for example. Other examplesof resistance variable materials include transition metal oxidematerials or alloys including two or more metals, e.g., transitionmetals, alkaline earth metals, and/or rare earth metals. Embodiments arenot limited to a particular resistance variable material or materials.For instance, other examples of resistance variable materials that canbe used as test materials on the test material structure include binarymetal oxide materials, colossal magnetoresistive materials, and/orvarious polymer based resistance variable materials, among others.

The material test structure illustrated in FIG. 1A includes portions ofthe test material 122 and the electrode material 124 formed oncantilever portions 108 and 110. The electrode material 124 can act as atop electrode for the material test structure. In a number ofembodiments, the electrode material 124 can be AlCu, Cu, Ta, TaN, TiN,TiAlN, Pt, Ti, TiO_(x), InSnO_(x), YBa₂Cu₃O_(7x), among other materials.The portion of the test material 122 and the electrode material 124formed on electrodes 120 is noncontiguous with the portion of the testmaterial 122 and the electrode material 124 formed on cantileverportions 108 and 110, which provides for the test material 122 andelectrode material 124 formed on the electrodes 120 to be separate fromthe test material and electrode material of adjacent material teststructures to avoid electrical shorts between adjacent test structures.The test material 122 and electrode material 124 can be formed using anon-conformal deposition process to form the noncontiguous portions ofthe test material 122 and electrode material 124. The electrodes 120 areformed in a dielectric material 114 and are recessed below cantileverportions 108 and 110.

The material test structure 150 includes a base region 103 comprising adielectric material 105 formed on a substrate material 101. A number ofconductive elements can be formed in dielectric material 105 and can beused to couple other elements of the material test structure 150 toselect device 128 and/or other circuitry associated therewith.Source/drain (S/D) regions 129-1 and 129-2 can be formed in substratematerial 101 to couple conductive elements to select devices.

The material test structure can include a select device 128 formed on asubstrate material 101. The select device 128 may be a field effecttransistor, e.g., metal oxide semiconductor field effect transistor(MOSFET), a bipolar junction transistor (BJT) or a diode, among othertypes of select devices. The select device 128 is coupled to anelectrode 120 of material test structure 150 via a conductive element126. Conductive element 126 is a conductive plug coupling electrode 120to conductive elements 123 and 125, which is coupled to a S/D region129-1 of select device 128. The conductive elements 123, 125, and 126can be comprised of tungsten (W), titanium nitride (TiN), tantalumnitride (TaN), tantalum (Ta), and/or copper (Cu), for instance.

In the example illustrated in FIG. 1A, test material 122 is formed onand coupled to a number of electrodes 120. One of the number ofelectrodes 120 that is coupled to the test material is also coupled to aconductive plug 126. The electrode 120 that is coupled to the conductiveplug 126 acts as a bottom electrode for the material test structure. Theconductive plug 126 can be formed of a conductive material, such astungsten (W), for example. The conductive plug 126 can couple the testmaterial 122 and an electrode 120 to the select device 128. The testmaterial structure can also include an electrode material 124 formed onthe test material 122. The electrode material 124 can act as a topelectrode for the material test structure. The test material structureincludes electrode material 124, test material 122, which can representan active material of a memory cell, and a bottom electrode 120, whichis coupled to the select device 128 by conductive plug 126.

Operation of material test structure 150 can include providing voltagedifferences between electrode 120 and electrode material 124 formed onthe test material 122 in order to determine various properties, e.g.,physical and electrical characteristics, of the test material 122. Thetest material structure can be used to determine how the resistance of atest material changes when different voltages are applied to thematerial test structure 150, for instance.

FIG. 1B illustrates a cross-sectional view of a material test structure160 having two levels of cantilever portions in accordance a number ofembodiments of the present disclosure. The embodiment illustrated inFIG. 1B includes the elements described in association with FIG. 1A andalso includes dielectric materials 112 formed on dielectric material 106and dielectric material 130 formed on dielectric material 112.Cantilever portions 116 and 118 of the dielectric material 130 areformed by removing portions of dielectric material 112. The testmaterial 122 and electrode material 124 can be formed on the cantileverportions 108, 110, 116, and 118 and on electrodes 120 of the materialtest structure. The portion of the test material 122 and the electrodematerial 124 formed on electrodes 120 is noncontiguous with the portionof the test material 122 and the electrode material 124 formed oncantilever portions 108, 110, 116, and 118, which provides for the testmaterial 122 and electrode material 124 formed on the electrodes 120 tobe separate from the test material and electrode material of adjacentmaterial test structures, e.g., to avoid electrical shorts betweenadjacent test structures.

In a number of embodiments, material test structures can includemultiple levels of cantilever portions. The addition of levels ofcantilever portions can provide increased likelihood and/or certainty ofphysical and electrical isolation of a material test structure fromother material test structures, for instance.

FIGS. 2A-2C illustrate various process stages associated with forming amaterial test structure in accordance with a number of embodiments ofthe present disclosure, e.g., a material test structure such asstructure 160 shown in FIG. 1B. FIG. 2B includes a dielectric material202 formed on a base region 203, e.g., a base region such as base region103 shown in FIG. 1. The base region 203 includes a dielectric material205, e.g., an oxide, formed on a substrate material 201, e.g., silicon.FIG. 2A illustrates a select device 228 formed in the base region 203.The select device 228 can be a field effect transistor, for instance.The base region 203 includes a number of conductive elements 223 and225, which can represent a metallization level used to electricallycouple portions of the material test structure to the select device 228,e.g., via source/drain regions 229-1 and 229-2, and/or to electricallycouple portions of the material test structure to various othercircuitry associated with testing material properties. Embodiments arenot limited to the example base region 203 shown in FIG. 2A. Forinstance, the base region may comprise various dielectric materials andmore or fewer conductive elements than those shown in FIG. 2A.

FIG. 2A illustrates a dielectric material 214 formed on dielectricmaterial 205 and conductive plug 226. The dielectric material 214 can bea nitride, such as silicon nitride (Si₃N₄), for example. A number ofelectrodes 220, which can function as a bottom electrode for the testmaterial structure, are formed in the dielectric material 214. Theelectrodes 220 can comprise materials such as copper, platinum,tungsten, silver, titanium nitride (TiN), tantalum nitride (TaN), and/orcarbon, among various other conductive materials and/or combinationsthereof. The electrodes 220 can be formed using a subtractive approachor a damascene approach, for instance. The electrodes 220 can be formedsuch that only one of the electrodes 220 is coupled to conductive plug226. A portion of the dielectric material 214 and the electrodes 220 canbe removed, e.g., via a CMP process.

FIG. 2B illustrates a process stage subsequent to that shown in FIG. 2A.FIG. 2B illustrates a dielectric materials 202, 204, 206, 212, and 230formed on the dielectric material 214 and the electrodes 220. In anumber of embodiments, a planarization process, e.g., CMP, can beperformed on an upper surface of dielectric material 214 and electrodes220 prior to formation of dielectric 202 thereon. In this example, adielectric material 204 is formed on the dielectric material 202, adielectric material 206 is formed on the dielectric material 204, adielectric material 212 is formed on the dielectric material 206, and adielectric material 230 is formed on the dielectric material 212. Thedielectric materials 202, 206, and 230 can be a nitride, such as siliconnitride (Si₃N₄), for example. The dielectric materials 204 and 212 canbe an oxide, such as silicon oxide (SiO₂), for example.

FIG. 2C illustrates a process stage subsequent to that shown in FIG. 2B.As shown in FIG. 2C, portions of the dielectric materials 230, 212, 206,204, and 202 can be removed. The portions of the dielectric materials230, 212, 206, and 204 can be removed via a selective etch process thatcan include dry etching and/or wet etching. Dielectric material 202 canact as a protective layer that protects dielectric material 214 andelectrodes 220 from the selective etch process that removes portions ofdielectric materials 230, 212, 206, and 204. The removal of the portionsof the dielectric materials 230, 212, 206, and 204 form cantileverportions 208, 210, 216, and 218 of the test material structure. Theselective etch process can form lateral recessions in dielectricmaterials 204 and 212, leaving portions of dielectric materials 206 and230 extending laterally from dielectric materials 204 and 212. Thecantilever portions 208, 210, 216, and 218 are formed in dielectricmaterials 206 and 230 due the lateral recessions formed in dielectricmaterials 204 and 212. The lateral recessions in dielectric materials204 and 212 can be formed in dielectric materials 204 and 212 becausethe etch rate of the dielectric materials 204 and 212, which can be anoxide, for example, is greater than the etch rate of dielectricmaterials 206 and 230, which can be a nitride, for example. Portions ofdielectric materials 202 can be removed via a dry and/or wet etchprocess to expose dielectric material 214 and electrodes 220. Also, theremoval the portions of the dielectric materials 230, 214, 212, 206, and204 can also form and isolate the test material structure from adjacenttest material structures, e.g., when forming an array of test materialstructures.

As shown in FIG. 1B, a test material 122 and an electrode material 124,which can act as the top electrode for the material test structure, canbe subsequently formed on the structure shown in FIG. 2C. The testmaterial 122 and electrode material 124 can be formed using anon-conformal process, such as physical vapor deposition (PVD). The testmaterial 122 and electrode material 124 can be formed on cantileverportions 108 and 112 of dielectric material 106, the cantilever portions116 and 118 of dielectric material 114, the dielectric material 114, andthe electrodes 120.

In a number of embodiments, forming the test material 122 and theelectrode material 124 on cantilever portions 108, 112, 116, and 118using a non-conformal process can create noncontiguous portions of thetest material 122 and electrode material 124 because the non-conformalprocess will not form the test material 122 and electrode material 124on the sidewalls of the dielectric materials 102, 104, and 112. Thenoncontiguous portions of the test material and electrode material 124are isolated from other portions of the test material and electrodematerial that may be associated with an adjacent material teststructure.

FIGS. 3A-3B illustrate cross-sectional views of material test structuresin accordance a number of embodiments of the present disclosure. FIG. 3Aillustrates a cross-sectional view of a material test structure 370having one level of cantilever portions in accordance a number ofembodiments of the present disclosure. The material test structure 370includes a test material 322 whose properties, e.g., physical and/orelectrical characteristics, can be tested and observed using thematerial test structure of the present disclosure. The material teststructure 370 can be used to simulate operation of a memory cell duringthe testing of different test materials. The test material 322 can be,for example, materials such as test material 122 described above.

The material test structure illustrated in FIG. 3B includes portions ofthe test material 322 and the electrode material 324 formed oncantilever portions 308, 310, 316, and 318. The electrode material 324can act as a top electrode for the material test structure. The portionof the test material 322 and the electrode material 324 formed oncantilever portions 316 and 318 and on electrodes 320 is noncontiguouswith the portion of the test material 322 and the electrode material 324formed on cantilever portions 308 and 310, which allows the testmaterial 322 and electrode material 324 formed on the electrodes 320 tobe separate from the test material and electrode material of adjacentmaterial test structures to avoid electrical shorts between adjacenttest structures. The test material 322 and electrode material 324 can beformed using a non-conformal deposition process to form thenoncontiguous portions of the test material 322 and electrode material324. The electrodes 320 are formed in a dielectric material 314, fromwhich cantilever portions 316 and 318 are formed. In a number ofembodiments, an etch process that removes portions of 320, 314, 312,310, 306, and 304 to form cantilever portions 308, 310, 316, 318 can beperformed subsequent to planarizing the surface of the electrodes 320and such that the electrodes 320 that interface with test material 322are not affected by the etch process. In a number of embodiments,electrodes 320 can be formed above and after cantilever portions 308 and310, allowing the test material 322 and electrode material 324 to beformed on the electrodes 320 without having process steps, such as anetch process, affect the surface of the electrodes 320 that interfaceswith the test material 322. In a number of embodiments, the testmaterial 322 can be formed directly after planarizing the surface of theelectrodes 320.

The material test structure 370 includes a base region 303 comprising adielectric material 305 formed on a substrate material 301. A number ofconductive elements can be formed in dielectric material 305 and can beused to couple other elements of the material test structure 370 toselect device 328 and/or other circuitry associated therewith.

The material test structure can include a select device 328 formed on asubstrate material 301. The select device 328 may be a field effecttransistor, e.g., metal oxide semiconductor field effect transistor(MOSFET), a bipolar junction transistor (BJT) or a diode, among othertypes of select devices. The select device 328 is coupled to anelectrode 320 of material test structure 370 via a number of conductiveelements 326 and 336. Conductive elements 323, 325, 326, and 336 areconductive plugs coupling electrode 320 to a metallization level 325,which is coupled to a S/D region 329-1 of select device 328. Theconductive elements 326 and 336 can be comprised of tungsten (W),titanium nitride (TiN), tantalum nitride (TaN), tantalum (Ta), and/orcopper (Cu), for instance.

In the example illustrated in FIG. 3A, test material 322 is formed onand coupled to a number of electrodes 320. One of the number ofelectrodes 320 that is coupled to the test material is also coupled to aconductive plug 326. The electrode 320 that is coupled to the conductiveplug 326 acts as a bottom electrode for the material test structure. Theconductive plug 326 can be formed of a conductive material, such astungsten (W), for example. The conductive plug 326 can couple the testmaterial 322 and an electrode 320 to the select device 328. The testmaterial structure can also include an electrode material 324 formed onthe test material 322. The electrode material 324 can act as a topelectrode for the material test structure. The test material structureincludes electrode material 324, test material 322, which can representan active material of a memory cell, and a bottom electrode 320, whichis coupled to the select device 328 by conductive plug 326.

Operation of material test structure 370 can include providing voltagedifferences between electrode 320 and electrode material 324 formed onthe test material 322 in order to determine various properties, e.g.,physical and electrical characteristics, of the test material 322. Thetest material structure can be used to determine how the resistance of atest material changes when different voltages are applied to thematerial test structure 370.

FIG. 3B illustrates a cross-sectional view of a material test structure380 having two levels of cantilever portions in accordance a number ofembodiments of the present disclosure. The embodiment illustrated inFIG. 3B includes the elements described in association with FIG. 3A andalso includes dielectric materials 306 and 312 formed on dielectricmaterial 304 and dielectric material 314 and electrodes 320 formed ondielectric material 312. In FIG. 3B, conductive element 336 is formed indielectric materials 306 and 312 to couple an electrode 320 toconductive element 326. Cantilever portions 316 and 318 of thedielectric material 330 are formed by removing portions of dielectricmaterial 312. The test material 322 and electrode material 324 can beformed on the cantilever portions 308, 310, 316, and 318 and onelectrodes 320 of the material test structure. The portion of the testmaterial 322 and the electrode material 324 formed on electrodes 320 isnoncontiguous with the portion of the test material 322 and theelectrode material 324 formed on cantilever portions 308, 310, 316, and318, which provides for the test material 322 and electrode material 324formed on the electrodes 320 to be separate from the test material andelectrode material of adjacent material test structures to avoidelectrical shorts between adjacent test structures.

In a number of embodiments, material test structures can include anumber of levels of cantilever portions. The addition of levels ofcantilever portions can provide increased likelihood and/or certainty ofphysical and electrical isolation of a material test structure fromother material test structures. Also, the addition of levels ofcantilever portions increases the aspect ratio of the conductiveelements that are used to couple an electrode to a select device.

FIGS. 4A-4F illustrate various process stages associated with forming amaterial test structure in accordance with a number of embodiments ofthe present disclosure, e.g., a material test structure such asstructure 380 shown in FIG. 3B, having two levels of cantileverportions. FIG. 4A includes a dielectric material 402 formed on a baseregion 403, e.g., a base region such as base region 103 shown in FIG. 1.The base region 403 includes a dielectric material 405, e.g., an oxide,formed on a substrate material 401, e.g., silicon. FIG. 4A illustrates aselect device 428 formed in the base region 403. The select device 428can be a field effect transistor, for instance. The base region 403includes a number of conductive elements 423 and 425, which canrepresent a metallization level used to electrically couple portions ofthe material test structure to the select device 428, e.g., viasource/drain regions 429-1 and 429-2, and/or to electrically coupleportions of the material test structure to various other circuitryassociated with testing material properties. Embodiments are not limitedto the example base region 403 shown in FIG. 4A. For instance, the baseregion may comprise various dielectric materials and more or fewerconductive elements than those shown in FIG. 4A.

The dielectric material 402 formed on base region 403 can be a nitride,such as silicon nitride (Si₃N₄), for example. In this example, adielectric material 404 is formed on the dielectric material 402. Thedielectric material 404 can be an oxide, such as silicon oxide (SiO₄),for example.

FIG. 4B illustrates a process stage subsequent to that shown in FIG. 4A.FIG. 4B illustrates an opening 430 formed by removing portions of thedielectric materials 402, 404, and 405, e.g., via a masking and etchingprocess. As an example, the opening 430 can be a circular via; however,embodiments are not so limited. As shown in FIG. 4C, a conductivematerial, such as tungsten, can be formed in the opening 430 to form aconductive plug 426. As described further below, the conductive plug 426can be used to couple an electrode of the material test structure toselect device 428.

FIG. 4C also illustrates a dielectric material 406 formed on thedielectric material 404 and the conductive plug 426. The dielectricmaterial 406 can be a nitride, such as silicon nitride (Si₃N₄), forexample. In a number of embodiments, a planarization process, e.g., CMP,can be performed on an upper surface of materials 404 and 426 prior toformation of dielectric 406 thereon. In this example, a dielectricmaterial 412 is formed on the dielectric material 406. The dielectricmaterial 412 can be an oxide, such as silicon oxide (SiO₂), for example.

FIG. 4D illustrates a process stage subsequent to that shown in FIG. 4C.FIG. 4D illustrates a conductive plug 436 formed in an opening 434. Theopening 434 can be formed by removing portions of the dielectricmaterials 406 and 412, e.g., via a masking and etching process. As anexample, the opening 434 can be a circular via; however, embodiments arenot so limited. The etch process used to remove portions of thedielectric materials 406 and 412 can end on the conductive plug 426 suchthat an upper surface of the conductive plug 426 is exposed. As such,the conductive plug 436 can be formed on the conductive plug 426. Theconductive plug 436 can be formed of a conductive material, such astungsten, for example. Although embodiments are not so limited, theconductive plugs 436 and 426 can be formed of the same material(s).

In the example shown in FIGS. 4A-4D, two separate conductive plugs 426and 436 are formed to create a conductive path through materials 412,406, 404, 402, and 405. However, embodiments are not so limited. Forinstance, in a number of embodiments, a single opening can be formedthrough the stack of materials 412, 406, 404, 402, and 405, and a singleconductive plug can be formed therein. However, a single via formedthrough the stack of materials 412, 406, 404, 402, and 405 may have anaspect ratio that is too high to provide for an effective conductivematerial fill. Forming separate conductive plugs can ensure a propercontact between the plugs, e.g., 436 and 426, and the conductive elementbeneath, e.g., conductive element 425. As such, the conductive plug 436has a smaller critical dimension, e.g., diameter, than the criticaldimension of the conductive plug 426.

FIG. 4E illustrates a process stage subsequent to that shown in FIG. 4D.FIG. 4E illustrates a dielectric material 414 formed on dielectricmaterial 412 and conductive plug 436. The dielectric material 414 can bea nitride, such as silicon nitride (Si₃N₄), for example. A number ofelectrodes 420, which can function as a bottom electrode for the testmaterial structure, are formed in the dielectric material 414. Theelectrodes 420 can comprise materials such as copper, platinum,tungsten, silver, titanium nitride (TiN), tantalum nitride (TaN), and/orcarbon, among various other conductive materials and/or combinationsthereof. The electrodes 420 can be formed using a subtractive approachor a damascene approach, for instance. The electrodes 420 can be formedsuch that only one of the electrodes 420 is coupled to conductive plug436. A portion of the dielectric material 414 and the electrodes 420 canbe removed, e.g., via a CMP process. The CMP process can form a contactsurface on which a test material can be formed.

FIG. 4F illustrates a process stage subsequent to that shown in FIG. 4E.As shown in FIG. 4F, portions of the dielectric materials 414, 412, 406,and 404 can be removed. The portions of the dielectric materials 414,412, 406, and 404 can be removed via a selective etch process that caninclude dry etching and/or wet etching. The removal of the portions ofthe dielectric materials 414, 412, 406, and 404 can expose dielectricmaterial 402 and form cantilever portions 408, 410, 416, and 418 of thetest material structure. The selective etch process can form lateralrecessions in dielectric materials 404 and 412, leaving portions ofdielectric materials 406 and 414 extending laterally from dielectricmaterials 404 and 412. The cantilever portions 408, 410, 416, and 418are formed in dielectric materials 406 and 414 due the lateralrecessions formed in dielectric materials 404 and 412. The lateralrecessions in dielectric materials 404 and 412 can be formed indielectric materials 404 and 412 because the etch rate of the dielectricmaterials 404 and 412, which can be an oxide, for example, is greaterthan the etch rate of dielectric materials 406 and 414, which can be anitride, for example. Also, the removal the portions of the dielectricmaterials 414, 412, 406, and 404 can also form and isolate the testmaterial structure from adjacent test material structures, e.g., whenforming an array of test material structures.

As shown in FIG. 3B, a test material 322 and an electrode material 324,which can act as the top electrode for the material test structure, canbe subsequently formed on the structure shown in FIG. 4F. The testmaterial 322 and electrode material 324 can be formed using anon-conformal process, such as physical vapor deposition (PVD). The testmaterial 322 and electrode material 324 can be formed on cantileverportions 308 and 312 of dielectric material 306, the cantilever portions316 and 318 of dielectric material 314, the dielectric material 302, thedielectric material 314, and the electrodes 320. The test material 322can be formed on the dielectric material 314 and the electrodes 320 suchthat the electrodes 320 are not affected by further processing on thematerial test structure after the formation and planarization of theelectrodes 320. The electrodes 320 are formed in and/or above thecantilever portions 308, 310, 316 and 318 allowing the test material 322to be formed on the electrodes 320 without having process steps, such asetching, affect the surface of the electrodes 320 that interface withthe test material 322. In a number of embodiments, an etch process thatremoves portions of 320, 314, 312, 310, 306, and 304 to form cantileverportions 308, 310, 316, 318 can be performed subsequent to planarizingthe surface of the electrodes 320 and such that the electrodes 320 thatinterface with test material 322 are not affected by the etch process.In a number of embodiments, electrodes 320 can be formed above and aftercantilever portions 308 and 310, allowing the test material 322 andelectrode material 324 to be formed on the electrodes 320 without havingprocess steps, such as an etch process, affect the surface of theelectrodes 320 that interfaces with the test material 322. In a numberof embodiments, the test material 322 can be formed directly afterplanarizing the surface of the electrodes.

In a number of embodiments, forming the test material 322 and theelectrode material 324 on cantilever portions 308, 312, 316, and 318using a non-conformal process can create noncontiguous portions of thetest material 322 and electrode material 324 because the non-conformalprocess will not form the test material 322 and electrode material 324on the sidewalls of the dielectric material 304 and 312. Thenoncontiguous portions of the test material and electrode material 324are isolated from other portions of the test material and electrodematerial that may be associated with an adjacent material teststructure.

As will be appreciated, elements shown in the various embodiments hereincan be added, exchanged, and/or eliminated so as to provide a number ofadditional embodiments of the present disclosure. In addition, theproportion and the relative scale of the elements provided in thefigures are intended to illustrate various embodiments of the presentinvention and are not to be used in a limiting sense.

Although specific embodiments have been illustrated and describedherein, those of ordinary skill in the art will appreciate that anarrangement calculated to achieve the same results can be substitutedfor the specific embodiments shown. This disclosure is intended to coveradaptations or variations of various embodiments of the presentdisclosure.

It is to be understood that the above description has been made in anillustrative fashion, and not a restrictive one. Combination of theabove embodiments, and other embodiments not specifically describedherein will be apparent to those of skill in the art upon reviewing theabove description. The scope of the various embodiments of the presentdisclosure includes other applications in which the above structures andmethods are used. Therefore, the scope of various embodiments of thepresent disclosure should be determined with reference to the appendedclaims, along with the full range of equivalents to which such claimsare entitled.

In the foregoing Detailed Description, various features are groupedtogether in a single embodiment for the purpose of streamlining thedisclosure. This method of disclosure is not to be interpreted asreflecting an intention that the disclosed embodiments of the presentdisclosure have to use more features than are expressly recited in eachclaim.

Rather, as the following claims reflect, inventive subject matter liesin less than all features of a single disclosed embodiment. Thus, thefollowing claims are hereby incorporated into the Detailed Description,with each claim standing on its own as a separate embodiment.

1-20. (canceled)
 21. A material test structure, comprising: a firstdielectric material formed on a second dielectric material, wherein thefirst dielectric material includes a first cantilever portion and asecond cantilever portion; a third dielectric material formed on afourth dielectric material, wherein the third dielectric materialincludes a third cantilever portion and a fourth cantilever portion; atest material formed on the first dielectric material and the thirddielectric material, wherein the test material includes a number ofnoncontiguous portions; and an electrode material formed on the testmaterial.
 22. The material test structure of claim 21, wherein the testmaterial comprises a resistance variable material.
 23. The material teststructure of claim 21, wherein the first and third dielectric materialscomprise a nitride.
 24. The material test structure of claim 21, whereinthe second and fourth dielectric materials comprise an oxide.
 25. Thematerial test structure of claim 21, wherein the test material iscoupled to a select device by a conductive plug.
 26. The material teststructure of claim 21, wherein a number of first electrode materialportions are formed in the third dielectric material.
 27. A materialtest structure, comprising: a first dielectric material having a firstcantilever portion and a second cantilever portion; a second dielectricmaterial having a third cantilever portion and a fourth cantileverportion, wherein the first dielectric material and the second dielectricmaterial are separate by a third dielectric material; a test materialformed on the first cantilever portion, the second cantilever portion,the third cantilever portion, and the fourth cantilever portion, whereinthe test material includes a number of noncontiguous portions; and anelectrode material formed on the test material.
 28. The material teststructure of claim 27, wherein the test material comprises a resistancevariable material.
 29. The material test structure of claim 27, whereinthe first and second dielectric materials comprise a nitride.
 30. Thematerial test structure of claim 27, wherein the third dielectricmaterial comprise an oxide.
 31. The material test structure of claim 27,wherein the test material is coupled to a select device by a conductiveplug.
 32. The material test structure of claim 27, wherein a number offirst electrode material portions are formed in the second dielectricmaterial.
 33. The material test structure of claim 27, wherein a numberof first electrode material portions are formed in a fourth dielectricmaterial.
 34. An array of material test structures, comprising: a numberof material test structures; wherein each of the respective materialtest structures include a first dielectric material having a firstcantilever portion and a second cantilever portion and a seconddielectric material having a third cantilever portion and a fourthcantilever portion; wherein a test material is formed on the first,second, third and fourth, cantilever portions; and wherein the testmaterial on the first, second, third, and fourth cantilever portions ofeach respective material test structure is noncontiguous with thematerial portion of an adjacent material test structure, such that thenumber of material test structures are electrically isolated from eachother.
 35. The array of claim 34, wherein an electrode material isformed on the test material on the first, second, third and fourth,cantilever portions of each respective material test structure.
 36. Thearray of claim 34, wherein the test material comprises a resistancevariable material.
 37. The array of claim 34, wherein the firstdielectric material and the second dielectric material are separated bya third dielectric material.
 38. The array of claim 34, wherein a numberof first electrode material portions are formed in the second dielectricmaterial.
 39. The array of claim 34, wherein a number of first electrodematerial portions are formed in a fourth dielectric material.
 40. Thearray of claim 34, wherein the second cantilever portion is locatedvertically above the first cantilever portion and the test materialformed on the second cantilever portion is noncontiguous with the testmaterial formed on the first cantilever portion.